Plasticizers are compounds or mixtures of compounds that are added to polymer resins to impart softness and flexibility. Phthalic acid diesters (also known as “phthalates”) are known plasticizers in many flexible polymer products, such as polymer products formed from polyvinyl chloride (PVC) and other vinyl polymers. Examples of common phthalate plasticizers include di-isononyl phthalate (DINP), diallyl phthalate (DAP), di-2-ethylhexyl-phthalate (DEHP), dioctyl phthalate (DOP) and diisodecyl phthalate (DIDP). Other common plasticizers, used for high temperature applications, are trimellitates and adipic polyesters. Mixture of plasticizers are often used to obtain optimum properties.
Phthalate plasticizers have recently come under intense scrutiny by public interest groups that are concerned about the negative environmental impact of phthalates and potential adverse health effects in humans (especially children) exposed to phthalates.
A known phthalate-free plasticizer for use in polyvinyl chloride (PVC) formulations is epoxidized soy oil. A growing number of applications require phthalate-free plasticizer to retain color when subjected to heat. However, epoxidized soy oil discolors when subjected to heat.
Accordingly, a need exists for a plasticizer having little, or no, phthalate with reduced, or no, discoloration when subjected to heat.